Dishwashing apparatus having improved pump means



Dec. 27, 1966 Ruspmo ETAL 3,294,102

DISHWASHING APPARATUS HAVING IMPROVED PUMP MEANS Filed Dec; 9, 1964 5Sheets-Sheet 1 uwE/vmfis Wazr 6 egez/ 2 1 )h mmwdcaq ATTORNEYS.

1966 J. G. RUSPINO ETAL 3,294,102 I I DISHWASHING APPARATUS HAVINGIMPROVED PUMP MEANS Filed Dec. 9, 1964 5 Sheets-Sheet 2 1966 J. G.RUSPINO ETAL 3,

DISHWASHING APPARATUS HAVING IMPROVED PUMP MEANS Filed Dec. 9, 1964 5Sheets-Sheet 5 NIH, Q il'gH NH,

United States Patent 3,294,102 DISHWASHING APPARATUS HAVING IMPROVEDPUMP MEANS James G. Ruspino, White Bear Lake, and Wilbur G.

Peyer, St. Paul, Minn., assignors to Whirlpool Corporation, acorporation of Delaware Filed Dec. 9, 1964, Ser. No. 417,045 3 Claims.(Cl. 134-186) This invention relates to a dishwasher and particularly toa pump having characteristics especially applicable for use in adishwasher.

In apparatus such as dishwashers, liquid washing and rinsing solutionsare circulated through the apparatus during a portion of the normaloperation. Then, at the end of each washing and rinsing operation theliquid is forced from the apparatus as to a drain.

In such an apparatus it is customary to use two centrifugal pumps, theimpellers of which are connected to a common rotatable shaft to effectsimultaneous rotation of the impellers in either of the two directions.When rotated in one direction, one pump circulates the liquid throughthe apparatus for washing or rinsing. Then, when rotation of the commonshaft is reversed, the second pump pumps the liquid from the apparatusas to a drain. One of the difliculties in a pumping system of this typeis that a loud and objectionable noise is created in the recirculatingpump, caused by liquid therein striking the impeller and pump housingand by cavitation as the liquid is drained from the apparatus by thedrain pump.

One of the features of this invention is to provide an apparatus such asa dishwasher having a pump for circulating liquid therein when rotatedin one direction and that is rotated in the opposite direction duringdrainage of liquid from the apparatus, together with means for ventingair into the recirculating pump during the reversal to substantiallyprevent noise caused by the presence of liquid therein and to reduce thepower requirement of the pump.

Other features and advantages of the invention will be apparent from thefollowing description of the invention taken in conjunction with theaccompanying drawings. Of the drawings:

FIGURE 1 is a fragmentary side elevational view partially in section ofthe lower portion of a dishwasher including a pumping system embodyingthe invention.

FIGURE 2 is a horizontal sectional view taken along line 2-2 of FIGURE1.

FIGURE 3 is a fragmentary vertical sectional view taken along line 33 ofFIGURE 2.

FIGURE 4 is a fragmentary sectional view taken along line 4-4 of FIGURE2.

FIGURE 5 is a horizontal sectional view taken along line 55 of FIGURE 4.V

In FIGURE 1 there is illustrated the lower portion of a dishwasherhaving a conventional front access door 11, liquid collecting sump 12 atthe bottom of a dishwashing tub 13 and a rotatable spray arm 14 forspraying liquid over dishes (not shown) during the washing and therinsing operation.

The sump 12 is provided with a liquid tight bottom 15 beneath which islocated an electric motor 16. The motor 16 is positioned between thebottom 17 of the dishwasher and the elevated bottom 15 of the sump.

The sump 12 is adapted to contain liquid 18 having a normal liquid level19. This liquid during washing of the dishes will normally be adetergent solution and during the rinsing will be water. Positioned inthe sump 12 and normally completely immersed in the liquid 18 is a firstcentrifugal pump 20 which is a recirculation pump (see FIGURE 3) thatincludes a housing 21 having a peripheral wall 22 and a bottom 23 whoseouter portion slopes 3,294,102 Patented Dec. 27, 1966 outwardly anddownwardly to adjacent the peripheral wall 22. This bottom 23 has asubstantially lowest area 24 adjacent the peripheral wall 22.

Extending upwardly from the motor 16 through the bottom 15 of the sump12 is the motor shaft 25. Mounted on the top of this shaft 25 is theimpeller 26 that is located within the housing 21 of centrifugal pump20'. This impeller 26 as is shown in FIGURE .5 has the usual pluralityof spaced curved blades 27 that tend to force the liquid outwardlytoward the peripheral wall 22 during regular rotation of the impellerwhich is the direction indicated by the arrow 29.

The bottom 23 of the pump housing 21 is provided with an inlet opening28 of the usual type arranged substantially concentrically with themotor shaft 25 and impeller 26. The opening 28 is generally circular andis of the diameter slightly smaller than the diameter of the circledefined by the inner edges of the impeller blades 27. The pump housing21 is mounted above the bottom 15 of the sump on spaced studs 30. Themotor 16 is suspended from spaced downwardly extending studs 31 from thebottom 15 of the sump 12.

The sump bottom 15 is shaped to define a second pump housing 32 for asecond pump 32A for draining the dishwashing apparatus 10. Metal plate33 is located across the top of housing 32 to define chamber 34. Themotor shaft 25 extends through this chamber 34, as shown in FIGURE 3,and has mounted thereon within the chamber an impeller 35 with aplurality of radial blades 36 extending therefrom. The auxiliary pumpchamber 34 communicates with the bottom of the sump 12 by inlet 33A andpassage 33B (FIGURE 2) that empties into the chamber 34 at a point (notshown) adjacent the outer diameter of impeller 36.

Leading from the drain pump chamber 34 is an exit conduit 37 whichempties into a drain 38. The conduit 37 is defined in part by anextension of the sump bottom g and drain pump housing 32 and .by the topmetal plate In this arrangement of the two pumps, the motor when used torotate the two pumps in one direction, which is the direction indicatedby the arrow 29 in FIGURE- 5, causes the recirculation pump 20 to drawliquid 18 in from the sump 12 through the inlet opening 28 and to forcethe liquid outwardly against the peripheral wall 22 in the usual manner.Leading from the top of the pump housing 21 is a recirculation conduit39 which directs liquid into the spray arm 14 in the customary manner.Then, when the motor is rotated in the opposite direction, or thedirection opposite to the arrow 29 in FIGURE 5, the curved nature of theimpeller blades 27 of recirculation pump 20 prevents the liquid 18 beingpumped from the sump 12 up the recirculation conduit 39 and causes thedrain pump impeller 35 of drain pump 32A to draw liquid 18 from the sump12 and discharge it out the conduit 37 and drain 38.

During this pump out period when the recirculation pump impeller 26 isrotated in a reverse direction (reverse to the arrow 29 in FIGURE 5) theliquid level 19 in the sump 12, of course, falls. During this reverserotation and without the corrective features of our invention, theimpeller blades 27 of the recirculation pump 20 will cavitate andproduce high shear forces on the water in housing 21 causing impact onthe impeller and housing 21, thereby creating a loud and objectionablenoise. However, with the addition of our vent means 40 (FIG- URE 4) airis drawn into the impeller area of housing 21 during reverse rotation ofimpeller 26 to displace the water in the impeller area to around theperiphery of housing 21.

When the liquid level 19 in sump 12 falls below the bottom of therecirculation pump impeller 26 during pump out, without the correctivefeatures of our invention there would be liquid in the pump housing 21.Reverse rotation of the impeller 26 under these circumstances wouldcause a considerable amount of objectionable noise in the recirculationpump 20 and thus in the dishwasher because the impeller blades 27 wouldbe striking this liquid.

In order to substantially eliminate this noise the present inventionprovides the means 40 for venting air into the pump housing 21 duringthe drainage of liquid 18 from the sump 12 which forces the water inpump 26 away from blades 27 of impeller 26. When the water level 19 insump 12 reaches a level below the inlet opening 28 of pump 20 the ventmeans 40 becomes ineifective and opening 44 drains housing 21 of furtherquantities of water to prevent collision of the blades 27 and the water.This venting means in the illustrated embodiment comprises the verticalopen end tube 40 which leads into the pump housing 21- to a pointadjacent the outer edges of the blades 27. The bottom of the tube 40communicates with a downward extending projection 41 within the pumphousing having on its inner edge adjacent the blades 27 an elongatedslot 42 (see FIGURE 4). The tube 40 is long enough so that its openupper end 43 is always above the maximum level 19 of the liquid 18 inthe sump 12. With this arrangement, as the liquid level 19 falls and asthe liquid level within the housing 21 falls correspondingly, air isbled into the pump housing 21 by way of the tube 41) and projection 41and opening 42. When impeller 26 is rotated during pump out in adirection reverse to its pumping direction, it forces a high speedstream of Water through the cutwater clearance area 47 toward projection41 (FIG. The low pressure area adjacent the high velocity stream inducesair through tube 40, projection 41 and slot 42 into the pump housing 21.The centrifugal field and Water recirculation paths between impellerblades 27 during this reverse rotation thereof provides the means forthe induced air to migrate to the center of the impeller 26. In thismanner water is displaced from the impeller 26. Now, the impeller blades27 no longer rotate in water and cavitation is eliminated. Therefore,the water in the pump housing 21 slows down so impact and shear forcesare reduced. The power consumption of the pump is reduced and theobjectionable noise is eliminated.

During normal operation of the pump impeller 26 in the direction shownby the arrow 29, some liquid is forced by the impeller 26 up through thetube 40 and projected toward the articles being cleaned, such as dishes(not shown) to aid the washing operation.

In FIGURE 3 there is illustrated a conventional air bleed tube 45 to theexit conduit 37 to prevent any siphoning of liquid from the drain 38 tosump 12 during the dishwashing operation. This tube 45 is provided withthe usual top inlet opening 46 for inflowing air.

Having described our invention as related to the embodiment shown in theaccompanying drawings, it is our intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but

rather be construed broadly within its spirit and scope as set out inthe accompanying claims.

We claim:

1. A dishwashing apparatus, comprising: means forming a liquid sump;means for removing liquid from said sump; pump means in said sumprotatable in one direction during normal dishwashing to pump liquidthrough the dishwashing apparatus and rotatable in the oppositedirection during removal of liquid from said sump; and means cooperatingwith said pump means for venting air into said pump means during saidopposite direction rotation to substantially prevent noise caused byliquid in said pump means and to substantially reduce the powerrequirements of said pump means during said liquid removal, said pumpmeans including a pump housing having an impeller means and a cut-Waterclearance area therein, said air venting means leading to adjacent bothsaid impeller means and said cut-Water clearance area.

2. The apparatus of claim 1 wherein said means for removing liquid fromsaid sump includes drain pump means operatively associated with saidsump, said circulating pump means having an outlet; means for jointlyrotating both said pump means in one direction to cause said circulatingpump means to pump liquid through said dishwashing apparatus and in thereverse direction to cause the drain pump means to remove said liquidfrom said dishwashing apparatus; and said air venting means venting airto said circulating pump means adjacent said outlet thereof during saidreverse direction rotation to substantially prevent noise caused byliquid in said circulating pump means and to substantially reduce thepower requirement of said drain pump means during said liquid removal.

3. A dishwashing apparatus, comprising: means forming a liquid sump;means for removing liquid from said sump; pump means in said sumpincluding a pump housing having an impeller means therein, said impellermeans being rotatable in one direction during normal dishwashing to pumpliquid through the dishwashing apparatus and rotatable in the oppositedirection during removal of liquid from said sump; and means for ventingair into said pump housing and said impeller means to displace liquidfrom said impeller means during said opposite direction rotation tosubstantially prevent noise caused by liquid in said pump housingimpinging on said impeller means during said liquid removal, said pumphousing including a cut-water clearance area therein, said air ventingmeans leading to adjacent both said impeller means and said cut-waterclearance area.

References Cited by the Examiner UNITED STATES PATENTS 3,018,650 1/1962Schmidt 68208 XR 3,082,779 3/1963 Jacobs 134-174 3,134,386 5/1964Jenkins 134-102 FOREIGN PATENTS 673,662 3/1939 Germany.

CHARLES A. WILLMUTH, Primary Examiner. R. L. BLEUTGE, AssistantExaminer.

1. A DISHWASHING APPARATUS, COMPRISING: MEANS FORMING A LIQUID SUMP;MEANS FOR REMOVING LIQUID FROM SAID SUMP; PUMP MEANS IN SAID SUMPROTATABLE IN ONE DIRECTION DURING NORMAL DISHWASHING TO PUMP LIQUIDTHROUGH THE DISHWASHING APPARATUS AND ROTATABLE IN THE OPPOSITEDIRECTION DURING REMOVAL OF LIQUID FROM SAID SUMP; AND MEANS COOPERATINGWITH SAID PUMP MEANS FOR VENTING AIR INTO SAID PUMP MEANS DURING SAIDOPPOSITE DIRECTION ROTATION TO SUBSTANTIALLY PREVENT NOISE CAUSED BYLIQUID IN SAID PUMP MEANS AND TO SUBSTANTIALLY REDUCE THE POWERREQUIREMENTS OF SAID PUMP MEANS DURING SAID LIQUID REMOVAL, SAID PUMPMEANS INCLUDING A PUMP HOUSING HAVING AN IMPELLER MEANS AND A CUT-WATERCLEARANCE AREA THEREIN, SAID AIR VENTING MEANS LEADING TO ADJACENT BOTHSAID IMPELLER MEANS AND SAID CUT-WATER CLEARANCE AREA.